Fuel pump



Nov. 27, 1934.

, A. HELDEN FUEL PUMP Filed hay 5, 193s Patented Nov. 2'77, 19341,981,913 FUEL PUMP Arthur Fielden, Detroit, Mich., assgnor to GeneralMotors Corporation, Detroit, Mich., a corporation of Delaware'application May 5, 1933, serial No. 669,491 s iaims. 01. 1oz-41) Thisinvention relates to pumps andespecially to pumps for the periodicdischarge of iiud at high pressure and in measured quantities.

It relates to injection pumps for* the supply 5 of fuel to an internalcombustion engine and to pumps in which a suitable bypass orrelief portor ports in communication with the pumping space is or are closed oropened to control the effective delivery and the beginning and end ofdischarge. Said pumps are adapted for use with a pressure loadeddelivery or dischargeA valve opened by the pump pressure and which mayconstitute an injection valve for the discharge of fuel at high pressurethrough suitable: spray holes into a combustion chamber. f

The invention relates particularly to such fuel pumps of the plungertype in which vthe valve action controlling the bypass-or relief portsias well as the pump inlet port is constituted by the stroke movementitself of the pump plunger and its cylinder relatively to one another.

One object of the invention is a fuel pump of the above general typewhich will be simple and cheap to manufacture which will have a minimumof ports andleakage. paths, a wide range of timing adjustment, and, inwhich there will be a preliminary bypass port opening into that part ofthe pressure space which is uppermost at a point higher than the inletport, open after the inlet port has closed on the delivery stroke,whereby any air mixed with the oil and which willof itself tend to riseto the highest point of the pressure space will be pumped out throughthis bypass port before discharge commences and before the high pressureof discharge which is developed immediately upon closure of this bypassport.

Another object of the invention is to control the beginning of dischargeand/or injection by the closure of the bypass port.

Another object' of the invention is to prevent the vbypass 'port fromfunctioning as an 'inlet port whereby the flow of oil entering the fuelpump will be in one direction and upwards, still further assisting inthe separation and escape of any air towards the upper end of thepressure space without the admixing iniluence of acontrary and opposingflow which would occur if the bypass port also functioned as an inletport.

A further object is to construct such a fuel pump in which there areonly two controlled ports both opening into a single annular chambersurrounding the cylinder barrel forming a reservoir for fuel at lowpressure from a suitable 55 source, one port servingas an inlet for fuelinto the cylinder. barrel and for relief of fuel out `from the cylinderto control the end ofinjection, and the other serving for bypass of fuelout`from the' cylinder before the beginning of injection and for controlof the beginning of injection.

A still further object of the invention is to combine an injection valveand'sprayer nozzle with.V such a fuel pump all in one unit assembly,having an air cushion chamber in the housing above the top end of theannular reservoir, and a leakage drain from the fuel pump constitutingalso an air vent for any air in excess of that required to flll the aircushion chamber.A

The accompanying drawing shows the application of the invention to aunit fuelv pump and injection nozzle in which the plungervis providedwithl oblique edges or helical lips controlling the beginning and.ending of injection and variable by turning thplunger whereby anearlier injection is accompanied by a later cutoff. The

rturning of the plunger is effected through a rack engaging a pinionloosely splined on the plunger so that the'latter is capable ofreciprocating motion through the pinion; In the drawing:

Figure 1 is a part sectional elevation of a combined fuel pump andinjection nozzle mounted in the cylinder head of an internal combustionengine.' e

Figure 2 is an enlarged perspective view of the 35 end of the plunger.

' Figure 3 is a section on line 3-3 of Figure l showing the means forangular turning adjustment of the plunger.

Figure 4 is a section on line 4-4 .of Figure 1 90 showing the means forlocating the cylinder bushing in the pump housing.,

Figure 5 is a perspective view of a suitable check valve for the bypassport to prevent the influx of oil into the cylinder barrel through thisport. 95

The pump plunger l has at its lower end an annular groove or space 2dividing the circumferential surface of the plunger into two parts. Thelower surface is bounded by the bottom circumferential edge l and ahelical edge 3 while 100 the upper surface has a helical edge 4. Achannel orduct 5 connects the annular space between the edges 3 and 4with the space below the end of the plunger.

The plunger works in a cylinder 6 which is a 105 bushing in a housing 7.Between the bushing and the housing is an annular chamber 8 formed by anenlarged bore of the housing. Two parts 9 and l0 through the wall of thebushing 6 conneet the annular chamber 8 with the bore of the 110bushing. These ports are on opposite sides of the .bushing to reduceinterference.

A duct 11 drilled through the upper part of the housing into the upperend of the annular chamber 8 serves for the supply of fuel to thisannular chamber from any suitable low pressure source. A similar duct 12has its outer end closed by a screwed plug 12' and constitutes an aircushion chamber.

Above the upper end of the bushing 6 the housing is counterbored to forma pocket 13 for a pinion 14 having a bearing formed by a boss 15extending into the bore of the housing and having a clearance betweenitself and the upper end of the bushing to leave a clearance space 16therebetween. The plunger 1 has a hexagonal splined portion 17 in thepinion 14 so that it may be turned thereby but is capable oflongitudinal reciprocating motion therein.

The pinion 14 may be angularly turned for adjustment of the beginningand end of injection by a rack 18 which can slide back and forth in ahorizontal groove 19 in the housing opening out into the pocket 13. Therack is retained in the groove by a plate 19'.

Above the pocket 13 the housing is counterbored to provide a pocket 20for a spring 21. The upper end of the plunger is provided with a head 22and a seating collar 23 for the spring 21. The other end of the springis provided with a seating collar24 resting in the bottom of the pocket20.

The upper end of `the plunger with its spring is enclosed by a cover 25which reciprocates in the pocket 20 under the influence of any suitabledriving means such as the rocking lever 26 with roller 27 for the downor pressure stroke of the plunger, the spring 21 effecting the return orsuction stroke of the plunger.

Below the bushing 6 the housing 7 is internally threaded for theinjection valve parts consisting of a nozzle piece 28, a valve seatpiece 29 and a distance piece 30 all within a bored out threaded cappiece 31 which screws into the housing.

The nozzle piece 28 has a conical seating in the cap piece 31 and allthree parts 28, 29, and 30 together with the bushing 6 are clampedtightly together and onto a shoulder 32 in the housing 7 when the cappiece 31 is screwed therein leaving a clearance space 33 between thebushing and the cap piece 31.

Ducts 34 through the piece 30 lead the fuel from a pocket 35 therein inopen communication with the pumping space below the plunger 1 to ducts36 leading to a chamber 37 in the piece 29. In this chamber 37 is aAseating for an injection valve 38 which has an area provided by ashoulder 39 so that it is lifted by the pressure of the oil in thechamber 37 to permit the flow of oil through a bore 40 in the piece 29and a bore 41 in the piece 28 to suitable spray holes 42.

The lifting of the valve 38 is resisted by a spring 43 in the piece 30acting on the valve through a collar 44 on a stem piece 45 for the valvewhich forms also a stop limiting the valve lift to a predeterminedamount.

The strength of the spring 43 and the loading it provides for theinjection valve 38 which is the loaded delivery valve of the pumpdetermines the minimum injection pressure.

A drain hole 46 from the clearane space 16 to the outside of the housingserves t drain away any oil which may leak between the plunger and theupper end of the bushing or between the upper end of the bushing and thehousing while a drain hole 47 from the clearance space 33 serves todrain away any similar leakage oil from the lower end of the bushing.The drain hole 46 will also serve as a vent for any air separating outfrom the fuel in the chamber 8 in excess of that 80 required to fill theair cushion chamber 12.

'I'he port 10 is provided with a check valve of any suitable type. Inthe example illustrated it consists of a flat spring 48 curved to ttightly in a shallow annular groove 49 around the bushing 85 6 with oneend over the port 10 and the other end locating and holding the springin position by a projection or dimple 50 formed thereon and sprung intoa corresponding depression 51 in the bushing.

The bushing 6 is located in the housing 7 with its ports 9 and 10 at afixed angular relationship to the plunger by a pin 52.

A small screw 53 through the housing 7 engages a slot 54 in the cover 25retaining the cover over 95 the plunger and its spring but permittingits reciprocating movement.

The complete assembly constitutes a unit fuel pump and injection nozzlewhich may be mounted in a suitable bore through the cylinder head of aninternal combustion engine.

As shown, the cap piece 31 of the combined fuel pump and injectionnozzle has a conical seating in a bore through a cylinder head 55 inwhich it is held by the studs 56. A suitable clearance between this boreand the housing 7 provides an annular space 57 into which the drainholes 46 and 47 may discharge any leakage. The annular space 57 isitself drained by a channel 58 in the cylinder head which returns theleakage oil to a supply tank not shown.

It will be noted that the lapped bore of the bushing 6 has beencounterbored at the upper end in order to eliminate the slight bellmouthing of the bore resulting from the lapping operation. The shoulder59 reduces the tendency for any fine gritty particles to be drawn inbetween the lapped surfaces as would otherwise be the case.

In operation, fuel at a small head of pressure is supplied to theannular chamber 8 through the 120 duct 11. In the position shown theplunger 1 is at the top of its stroke and has uncovered the inlet port 9allowing oil to flow into the pumping space over and above the oilalways remaining in the pocket 35 the ducts 34 and 36 and the chamber37, 125 and to rise through the channel 5 and into the annular space 2in the plunger. As the plunger descends it rst covers the inlet port 9and then pumps oil and any air bubbles mixed therewith up through thechannel 5 and out through the bypass 130 port 10 back into the annularchamber 8 until the edge 4 covers the port 10. At this point and therenow being no other outlet from the pumping space, the pressure risesrapidly in the pumping space and its connections with the chamber 37contain- 135 ing the spring loaded valve 38 until the pressure on theexposed area of the valve is suicient to lift the valve off its seat andthe oil is injected into the engine cylinder through the spray holes 42./The injection continues under the influence of the downwardly movingplunger until the edge 3 uncovers the port 9 which now functions as apressure relief port terminating the injection and bypassing theremaining oil delivered by the plunger 145 from the pumping spacethrough the channel 5, into the annular space 2 and back into theannular chamber 8.

'I'he air chamber 12 acts as a pressure accumulator, reducing thepressure variations on the inlet 15a side of the pump as a result of theopening and closing of the ports 9 and 10.

The capacity of the chambers and passages on the pressure side of thepump is sufliciently small and there are no valves between the effectiveinjection pumping space and the injection valve itself so thatpractically no delayed closing of the injection valve occurs as a resultofthe compressibility of the fluid when the port 9 is opened toterminate injection.` e

While the pump might be operated without the check valve 48 over thebypass port 10 in which case oil could flow into the pump cylinderthrough the port 10 as well as the port 9, there would be a ow inopposite directions through the passage 5 both at the same time, with anadmixing influence on the fuel and any air bubbles entering the pumpchamber. With a check valve over the port 10 preventing the flow of oilinto the cylinder through this port the oil taken into the pump willalways flow in one direction and upwards through the passage 5. This isthe direction in which-any air bubbles tend themselves to rise and hencetheir separation towards the top of the annular space 2 is assisted andsince a part of the charge is always bypassed through the port 10 beforeinjection the possibility of any air interfering with the injection ofoil into the engine cylinder is reduced.

I claim:

l. In a fluid pump, in combination, a cylinder,

' a plunger cooperative therewith as a pump for the pressure dischargeof fluid from the cylinder through a. delivery outlet provided with aloaded delivery valve, a pair of ports and coacting control edgestherefor on the cylinder and plunger, cornprising an inlet port andabypass port spaced from each other, the bypass port opening from thatpart of the pressure space which is uppermost, at a point higher thanthe inlet port and the aforementioned delivery outlet, the ports andcontrol edges together providing for bypassing of fluid, including anyair or gas bubbles, out from the uppermost part of the pressure spacesof the pump cylinder-after the closing of the inlet port and before thepressure discharge through the loaded delivery valve, forthe beginningof pressure discharge upon closure of the bypass' port and for closureof the delivery valve by the opening of one of the ports to relievethe'uid pressure after the dischargeof a measured quantity of fuelthrough the delivery valve. y v

2. A fluid pump according to claim 1, in which termination of thepressure discharge is effected by the opening of the inlet port torelieve the fluid pressure.

3. In a fluid pump in combination, a cylinder, a plunger cooperativetherewith as a pump for the pressure discharge of fluid from thecylinder through a delivery outlet provided with a loaded deliveryvalve, a pair o1' ports and coacting control edges therefor on thecylinder and plunger comprising an inlet port and a bypass port spacedfrom each other, the bypass port opening from that part of the pressurespace which is uppermost, at a point higher than the inlet port and theaforementioned delivery outlet, said bypass port being provided with acheck valve permitting the flow of fluid out from the cylinder butpreventing the flow of fluid into the cylinder, the ports and controledges together providing for bypassing of fluid out from the uppermostpart of the pressure space of the pumpcylinder after the closing of theinlet port and before the pressure discharge through the loaded deliveryvalve, for the beginlthe pump the inlet port is rst closed by the end ofning of pressure discharge upon closure of the bypass port and forclosure of the delivery valve by the opening of one of the ports torelieve the fluid pressure after the discharge of a measured quantity offuel through the delivery valve.

4. A fluidpump according to claim 3, in which termination of thepressure discharge is effected ,by the opening of the inlet port torelieve the fluid pressure. v

. 5. In a fluid pump in combination, a cylinder, a plunger cooperativetherewith as a pump for the pressure discharge of ,fluid from thecylinder through a loaded delivery valve, coacting ports and control,edges therefor-on the ,cylinder and plunger including an inlet port anda bypass port, a check valve in the bypass port preventing the flow offluid into Vthe pump pressure space, the bypass port opening from thatpart of the pressure space which is uppermost at a point higher than theinlet port, the ports and the control edges for the ports being soarranged and disposed that the bypass port is open after the inlet porthas closed on the delivery stroke of the pump, all whereby fluid entersthe pump only through the inlet port and rises upward and a part of thepump charge is expelled through the bypass port from the uppermost partof the pressure space after the closure of the inlet port and before thehigh pressure of discharge through the delivery valve which is developedimmediately upon closure 105 of the bypass port.

6. A fluid pump according to claim 5 in which termination of thepressure discharge is effectedby the opening of the inlet port torelieve the fluid pressure. 110

7. In a fluid pump in combination, a cylinder, a plunger in thecylinder, a delivery outlet provided with a loaded delivery valve forthe pressure discharge of uid from the cylinder, an inlet port and abypass port in the cylinder, said bypass port 115 opening from that partof the pressure space which is uppermost, at a point higher than theinlet port and the delivery outlet, and control edges for the portsconstituted by the end of the plunger and the two edges of an annulargroove thereon said groove being in continuous communication with thepressure chamber of the pump whereby on the delivery stroke of the pumpthe inlet port is first closed by one edge, the bypass port is nextclosed by another edge to control the beginning of discharge through theloaded delivery valve, and one of the ports is finally opened by theotherwise unused edge to relieve the pressure and terminate dischargethrough the delivery valve.

8. In a fluid pump in combinatioma cylinder, 130 a plunger in thecylinder, a delivery outlet provided with a loaded delivery valve forthe pressure discharge of'fluid from the cylinder, ports including aninlet port and a bypass port in the cylinder, said bypass port openingfrom that part of the pressure space which is uppermost, at a pointhigher than the inlet port and the delivery outlet, and control edgesfor the ports constituted by the end of the plunger and the two edges ofan annular groove thereon such that on the delivery stroke of plunger,the bypass port is next closed by one edge of theannular groove tocontrol the beginning of discharge through the loaded delivery valve,and the inlet port is finally opened by the other edge .I 45 offiz/heannular groove to relieve the pressure and terminate discharge throughthe delivery valve.'

.ARTHUR HELDEN.

CERTIFICATE 0F CORRECTION.

Patent No. 1,981, 913. November 27, 1934.

ARTHURA MELDEN.

lt is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 3,line 140, claim 8, strike out the words "such that" and insert insteadsaid groove being in con tinuous communication with the pressure chamberof the pump whereby; and that the said Letters Patent should' be readwith this correction therein that the same may conform to the record ofthecase in the Patent Office.

Signed and sealed this 12th day of February, A. D. 1935.

Leslie Frazer (Seal) Acting Commissioner of Patents.

